The Tu-at is the underworld in Tarna and Egypt.
Background[]
It is the place where people in Tarna (& Egypt) go when they die. Anubis weighs the souls of the dead to determine their worthiness. Once they are weighed, and if they are found worthy Sekhmet takes their soul.
Khatib Mukar'ram did not rise as a ghost. His Ka was weighed by Anubis, and he was allowed to stand at Sekhmet's side.